This invention generally relates to an apparatus for illuminating a sign through a fiber optical cable and more specifically to a device with which light from light source can be smoothed to produce a more uniform distribution.
Devices are known with which light from a high intensity source, such as a metal halide bulb, is distributed to a remote site through an optical fiber cable. The light from such source, however, is not always uniformly distributed over the bulb""s surface area. Hence, variations both in color and intensity tend to arise and the variations are faithfully reproduced by the optical fiber cable at the latter""s distal end. Hence, some of the fibers illuminate an object with unevenly distributed light and this unevenness becomes visibly apparent and frequently undesirable.
This unevenness in light distribution tends to change or shift around with aging of the light source and thus cause different fibers to project different light intensities as brown colored or sulfur-related deposits form on the inside of the light bulb. There thus exist a need to provide a uniform light distribution at the from an uneven light source over its life span and particularly at the end of an optical fiber cable whose proximal end receives light from the source.
With an apparatus in accordance with the invention one can even out unequal distributions of light from a light source such as an intense halide light bulb. This is achieved with an elongate light blending transparent conduit positioned to intercept light from the light source at one end. The light blending conduit has sufficient length to enable light from the source to be subjected to multiple reflections from an internal wall and thus produce a substantially even distribution of light at the other end of the conduit.
With an apparatus according to the invention an intense light source can be distributed by a fiber bundle to a remote location with an even distribution of light so that each light fiber delivers substantially the same intensity. As a result the optical fibers can illuminate an object such as a sign in an even manner even when the light source itself may have light discontinuities across its surface. The effect of the light blending conduit enables one to preserve a uniform light distribution even as the light source itself changes over time and develops yellow or dark spots that would be visibly disturbing at the object illuminated by the light source.
It is, therefore, an object of the invention to provide an apparatus with which light from an uneven light source can be delivered with a uniform distribution and with low losses to effectively reduce heating of the conduit from light incident from a high intensity light source.
It is a further object of the invention to provide an apparatus with which light from an intense source such a metal halide bulb can be delivered by an optical fiber bundle onto an object with an even distribution of light from the fibers.
It is still further an object of the invention to provide an apparatus with which light from a high intensity source such as a metal halide bulb can be dimmed without disturbing the even light distribution provided by a light blender positioned to receive focused light from the source.
These and other advantages and objects of the invention can be understood from a detailed description of the drawings as briefly described below.